As background art of the present technical field, there is a JP-A-2009-170014 (PTL 1). In order to minutely position a recording and reproducing element that faces the surface of a recording medium in a magnetic disk apparatus to record and reproduce information, the configuration of a magnetic head slider in which a pair of electrothermal actuators are arranged via a thermal expansion member on both sides of the recording and reproducing element in a width direction of tracks is described in paragraphs 0077 to 0081 and FIGS. 6 and 7 of this publication. Additionally, the configuration of a control system that controls the driving of the pair of electrothermal actuators and a voice coil motor and positions the recording and reproducing element is described in paragraphs 0082 to 0091 and FIG. 8 of this publication.
On the other hand, as other background art of the present technical field, there is a JP-A-2006-164414 (PTL 2). The configuration of two electrothermal actuators for making a magnetic head element that performs a reading element and writing protrude with respect to the surface of a magnetic disk on which information is recorded is described in paragraphs 0042 to 0046 and FIGS. 5 to 7 of this publication. The two resistors are connected to two diodes having mutually opposite polarities in series, respectively, and circuits of these two systems are connected in parallel. Supply of currents to the resistors is performed via the two parallel connection points.